To mask their odor from rattlesnakes, California ground squirrels and rock squirrels chew on sloughed-off snake skin and smear it on their fur, according to a new study. The act most likely persuades the predators that another snake, not a squirrel, is in the area.

“To our knowledge this is the first case where [this idea] has been tested systematically and shown to have an anti-predator function—protecting the squirrel from rattlesnake predation,” said study lead author Barbara Clucas.Rattlers and other snakes usually prey on baby squirrels, because the adults have proteins in their blood that make them immune to snake venom.

Pups, on the other hand, aren’t big enough to resist the poison. Clucas and colleagues therefore think that adult female and juvenile squirrels spend more time applying snake scent to their bodies. “Adult females actively protect their pups … and share their burrows with juveniles,” Clucas said.